1. Field of the Invention
The present invention relates to a novel photo-polymerizable composition.
2. Description of the Prior Art
The photo-polymerization method is extremely important in the preparation of photo resists, light-sensitive printing plates or the like. Heretofore, as the photopolymerization process, a free radical process wherein polymerization is initiated by free radicals produced by the action of light has been employed. However, this free radical process has serious disadvantages in that this reaction is inhibited by molecular oxygen, and in that monomers which can not be polymerized by initiation with free radicals cannot be used.
A polymerization reaction initiated by a cation, i.e., a cationic polymerization process, is also well known in the field of high polymer chemistry. For example, a description of this process is given in P. J. Flory; "Principle of Polymer Chemistry", p.217 et seq., Cornell Co. Ltd., As the initiator of this cationic polymerization, there are Lewis acids, i.e., compounds capable of accepting an electron pair, proton acids, i.e., compounds capable of releasing a proton, and the like. As examples thereof, boron trifluoride, aluminum chloride, hydrogen halogenide, sulfuric acid, etc. are known.
As the compounds known as the so-called photo cationic polymerization initiators capable of releasing a cationic polymerization-initiating agent upon being exposed to light, there are, e.g., the boron fluoride salts of aromatic diazonium compounds described in Belgian Pat. No. 593,648; and the polyboron salts described in U.S. Pat. No. 3,196,098 and Japanese patent publication No. 27561/68.